The Arroyo Aguaray Guazú is a watercourse located in the province of Misiones, Argentina, belonging to the hydrographic basin of the río Paraná, into which it ultimately drains. The stream originates in the foothills of the Sierra Morena, within the departamento de General Belgrano, and flows in a predominantly westward direction throughout its entire course before emptying into the Paraná north of the locality of María Magdalena. Its drainage basin covers approximately 873 km².

The channel pattern is dendritic-pinned-meandering, reflecting a combination of branching tributary networks and winding reaches. The arroyo forms part of the boundary between the departamentos de Iguazú and Eldorado. Notable tributaries include the arroyos Aguaray Miní and Dorado, both entering from the right bank. The stream is characterized by a significant number of riffles and rapids throughout its course, which paddlers should factor into route planning and skill assessment.

The arroyo passes through or near the locality of Puerto Esperanza with clear and transparent waters. The surrounding riparian vegetation is dense and includes native tree species such as Loro negro, Lapacho, and Guatambú, along with vines and epiphytes. Wildlife along the banks and in the water includes toucans, hummingbirds, various parrot species, and a range of fish, reptiles, and amphibians.

Portions of the arroyo's watershed fall within protected areas, including the parque provincial Esperanza, the refugio privado Aguaray Miní, and the parque natural municipal Lote C. Paddlers planning trips in or near these protected zones should verify any applicable regulations before entering.